It’s caused by a build-up of fluid in soft tissues at the end of the fingernails, added Cancer Research UK.

The NHS said: “Clubbing of the fingertips can run in families and be entirely harmless.

“However, if it suddenly develops, it may be a sign of one of many underlying medical conditions, including long-term lung disease or heart disease, inflammatory bowel disease, and cirrhosis of the liver.”

Other lung cancer symptoms include a cough that doesn’t go away, persistent chest infections, or coughing up blood.

Signs of the condition tend to get worse over time, and the symptoms are usually difficult to spot during its early phases.